This invention relates specifically to the pressure swing method of generating breathing oxygen utilizing a particular type of complex inorganic silicate known as "molecular sieve", which has an affinity for nitrogen, carbon monoxide, carbon dioxide, water (vapor) and all hydrocarbons, but freely passes oxygen and other gases. By a method known to those well versed in this science, this material is packed into cylindrical containers, in order to create what is known as sieve beds. These containers are then selectively subjected to a stream of compressed air, resulting in oxygen enriched air at the outlet port of the sieve beds. Various mechanical and electronic components have been utilized in known prior art devices in an effort to time and regulate the internal operating parts which bring about the necessary steps of alternately charging the sieve beds with compressed air, and then back flushing or purging them of nitrogen and the other captured gases.
The novel valve in accordance with this invention is intended as a simple reliable alternative for all the "over engineered," unnecessarily complicated components and parts that characterize the state of the art devices now being used to generate breathable oxygen in home use machines.
Home use oxygen concentrators come in many sizes and shapes, and such prior art devices share two important things in common:
First, they are extremely valuable devices for respiratory patients who require around the clock oxygen therapy. They manufacture breathing oxygen instantly on the spot, as it is used. The oxygen concentrators therefore eliminate the need, bother and expense of the familiar large green oxygen tanks, which are regarded by many as quite dangerous because of the very high pressure to which they are typically charged.
Second, the prior art devices are finicky, prone to malfunction, and very expensive, complicated "busy" machines.
Generally, all prior art oxygen concentrators in public use today consist of three basic components;
1. An air compressor. PA1 2. One or more molecular "sieve beds". PA1 3. A combination of various mechanical and electronic devices designed to time, regulate, charge, and purge the molecular sieve bed(s).
Item #3 above represents the area where mechanical failure is most common in these machines, and it is this area that the rotary pressure/purge valve in accordance with this invention directly addresses. It is also the area that usually results in an inordinate financial burden largely due to the fact that when a timing or regulating device fails, it almost always destroys the oxygen producing capability of the molecular sieve beds. Simple internal failures of an oxygen concentration machine therefore usually escalate to a major failure, requiring sieve bed replacement and total overhaul of the machine, costing several hundred dollars. It is because of these undesirable shortcomings of present day prior art machines, that the novel valve in accordance with this invention was developed in an effort to improve reliability.
As in the rotary valve system utilized in the U.S. Pat. No. 4,272,265 to Fred P. Snyder, the instant rotary valve also uses internal rotating components to control pressurization and purging of the molecular sieve beds. These internal components are, however, of a different type, composition and function.
Whereas the Snyder rotating components consist of two flat plate discs with drilled holes at a specific angular relationship, the present invention utilizes sector shaped components making possible the attainment of a novel and highly advantageous pressure overlap feature as will be seen hereinafter in FIGS. 10 and 11, that greatly increases flexibility and efficiency, and entirely eliminates the undesirable pulsations in the oxygen output flow that characterized the functioning and operation of the prior art, as will be hereinafter noted from FIGS. 8 and 9.